File and similar abrading-tool.



T. BOSWELL. .IILE AND SIMILAR ABRADING TOOL.

APPLICATION TILED DEC. 29, 1908.

9 0 9 1 L 2 Lb p 8 S d 8 LIU. n e t a P s E w M m W iirirr THOMAS BOSWELL, 0F SHEFFIELD, ENGLAND.

FILE AND SIMILAR ABRADING-TOOL.

Specification of Letters Patent. Patented Sept. 21, 1909.

Application filed December 29, 1908. Serial No. 469,855.

To all whom it may concern:

Be it known that I, THOMAS BoswnLL, a subject of the King of Great Britain and Ireland. residing at Sheflield, in the county of York. England. have invented new and useful Iiiiprovemeiits'in Files and Similar Abradbig-Tools, of which the following is a specification.

The object of my invention is to improve the abradiiig or cutting power of tiles and the like.

Referring to the drawings, which form a part of this specification: Figure 1 is an eleration or plan of part of the tang end of a tile, the face of which is cut or formed according to my invention. Fig. 2 is a magnified perspective view of art of-tlie face of the file looking almost edgewise of it in the direction of the arrow on Fig. 1. Fig. 3 is a magnified section of a row of teeth taken on the line a-(z of Fi 2.

In carrying my said invention-into effect I depart from the usual method of cutting a tile by means of a series of straight cuts diagonally across the face thereof and crossing each other at an angle, and substitute thoi'et'or a series of curved cutscitliercrosscd by other curved cuts or by diagonal straight cuts.

Referring to Fig. 1 of the di'awiiws, the straight cuts b are .first imparted to the file, while the curved cuts 0 are made afterward. This operation may be reversed if desired, the curved cuts being made first and the straight cuts last. Again, the curved cuts 0 of small radius may he first imparted to the surface of the file and curved cuts of larger radius afterward given or imparted to the said surface. This procedure may again be reversed if desired. Further, it is not essential to the'latte r application of my invention that the curved cuts in one direction he of a ditterent radius or curve to those in the 0pposite direction.

Although I have'described severaldifi'erent ways of producing the desired tooth I am of opinion that in practice the best results are obtained from the method of cutting first described. when the curved cuts are of a fairly large radius and crossed by either long straight cuts as shown. upon Fig. 1 or by other curved cuts of much greater ra dius. the size of the tooth is kept more even from one side to the other when the above 'iiietliods are adopted. Although the size of the tooth increases slightly from one side of the tile to the other the cutting power is not materially ati'ected thereby. The cutting of the file face may be done with an ordinary file cutting machine having a fixed chisel therein.

It will be noticed upon referring to Figs. 2 and 3 that the tooth produced is of an arch shape viewed from the front or cutting side and tapers away rapidly and diagonally backward, thus insuring a highly etlieiei t cutting power and ainpler clearance backward for getting rid of the waste metal or the like. cut away, than is Oblfillltd'lll a file cut in the ordinary way. consequently more work is got through in a given time.

l am aware that it. has been proposedto form a tile or abi'ading surface with a series of concentric cuts, but curved cuts have hot to my knowledge been crossed diagonally with other either curved or straight cuts.

Having described my invention, what I claim as new and desire to secure by Letters Patent is A tile having its teeth formed by a parallcl series of long straight diagonal cuts crossed by a series of curved cuts having their arches arranged convex with the direction ot'the file stroke.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

' THOMAS BOSWELL.

Witiiesses Lii'riinii J. PARR, CHAS. N. DANIELS. 

